Trypanosomiasis in macaques has now been discovered to involve an area extending approximately 2600 miles north to south and about 3000 miles east to west. The primate trypanosomes involved are a varied, nonidentical group, some are new species, i.e. Trypanosoma cyclops, an unusual, perhaps unique pigmented trypanosome, non of the natural vectors are known. Investigations will be carried on in the field (chiefly Malaysia) and in the United States. Objectives of the field work are to determine (1) the possible public health relevance and medical importance of the newly found primate trypanosomiases of Asia, (2) whether Chagas' Disease caused by Trypanosoma cruzi is indigenous in Asia, (3) the locality of transmission areas through the use of sentinel monkeys, (4) collection of wild insects from transmission areas to determine possible wild vectors. Laboratory work in the United States will center on: (1) Identification of 40 isolates of trypanosomes obtained from jungle primates. These include microorganisms obtained from three geographical sources: Indonesia, Malaysia and India. Studies will focus on growth characteristics, morphology, animal infectivity, evolution in insects and, if warranted, on sensitivity to chemotherapeutic agents. (2) Evaluation of two new immunological tests, each prepared with specific culture antigens, for use in the diagnosis of trypanosomiasis. (3) Utilization of the Asian trypanosomes for special cell studies due to certain useful characteristics, i.e. split kinetoplast-basal granule complex, pigment marker, tendency to confluent growth.